Programmable sequential control means having a plurality of control circuits for controlling a respective plurality of discrete suboperations

ABSTRACT

A control means for controlling sequences of events or working operations in machinery and plants. The control means is particularly advantageous in that it is able to control sequences which are going on simultaneously or partly simultaneously and which are dependent or independent of each other. This is by virtue of a control circuit which responds to two concurrently applied input signals to generate a signal if a predetermined one of these signals arrives earlier than the other and if said circuit beforehand has been set in a responsive condition by means of a third input signal, the generated signal being supplied to program means for controlling the sequences of the working operations.

United States Patent Nyman July 3, 1973 [54] PROGRAMMABLE SEQUENTIALCONTROL 3. l78.73l l H1969 Morton et Bl l37/8L5 X MEANS HAVING A p u -y01: 3,550,606 12/1970 Thorburn 137/8l.5 m CONTROLLING i223??? i133:227122313533: 1.1115512??? A RESPECTIVE PLURAUTY DISCRETE 3,612,90610/1911 Kflflmdym. 340/1125 x SUBOPERATIONS 3,620,127 11/191111161611611 I37l624.l8 x

Bengt Ebbe Harald Nyman, Rockford, ill.

Atlas Copco Aktiebolag, Nacka, Sweden Filed: Apr. 22, 1970 Appl. No.:30,909

inventor:

Assignee:

OTHER PUBLICATIONS l-ladekel, R1, Automatic Sequencing Circuits inAutomation, June, 1958; pp. 69-76 [30] Foreign Application Priority Data57 ABSTRACT Apr. 25, Sweden A n l means for con ing eq e f events orworking operations in machinery and plants. The confi i Moll-71$; 372/8troi means is particularly advantageous in that it is able r' 3 3 5 g tocontrol sequences which are going on simulta- [5 l e 7 i neously orpartly simultaneously and which are depen- 30 [232 2 13 l8 6 I628 dentor independent of each other. This is by virtue of a control circuitwhich responds to two concurrently applied input signals to generate asignal if a predeter- [56] References (med mined one of these signalsarrives earlier than the other UNITED STATES PATENTS and if said circuitbeforehand has been set in a respon- 3,4l4.884 12/1968 Jensen 340/1725sive condition by means ofa third input signal, the gen- 3,467,9489/1969 Barlow et al 340/1725 erated signal being supplied to programmeans for con- Turcotte X trolling the sequences of the workingaperations 3,484,700 12/1969 Armstrong...................... 307/218 X3,410,310 11/1968 Ray 131/6215 19 Claims, 23 Drawing Figures F" Yrs(CONTROL CIRCUIT) I MEMORY I i PART I ".2-l- 7 '5- 1 D U INPUT PART e 2I 3 1 ourau'r 1 PART PATENIED JUL 3 973 SHEET 03 OF E: KOINI EEF I IPAFENIEBJUL 31m 3 744 029 saw 05M 13 Wm 5 seuson 23 MOTOR I o-I i' gm-"2! I I I LIMIT M I 3,1 I I I I 33;; I I I I MOTOR I M f I I f I J I 525 I I CARRIERS l l VALVE \P I 162 "12 k l: E?

I i "22 I I LIMIT M l I I I SENGSOR I I I I I fl,22 I I I h H I, uo'ronI v I I G72 I '33 $357? I \l PATENTEDJUL 3l973 3.744.029

SHE? 070! 13 LOGIC PLATE 5! (STEP MODULE) TlMlNG DEVICE l0 AMPLIFIERFIG. 7a

PAIENIEIJJuL 3 ms SHEEI 08 HF SNSTEP MODULES) FIG. 7b

PAIENTEDJUL 3cm 3.744.029

SHEET OEIBF 13 PATENTEDJUL 3:975 3.744.029

SHEET 100F 13 PAIENTEO HL 1 3.744.029

sum 12M 13 DISTANCE F St T G A 60 7 H sr TIME mwuLE 5:, 51 5: 5: sr 515r;- sr

FIG. 77b

STEP SUCCESSION WOIQEI N DESICES 0 5+ F+ 0+ H+ PROGRAMMABLE SEQUENTIALCONTROL MEANS HAVING A PLURALITY OF CONTROL CIRCUITS FOR CONTROLLING ARESPECTIVE PLURALITY OF DISCRETE SUBOPERATIONS BACKGROUND OF THEINVENTION This invention is directed to a control system for sequentialcontrol of such events or operations which only have to be started andthen continue by themselves until they either are stopped by themselvesor stopped by the control system. Examples of such operations areworking operations which are carried out in production plants bymultioperation working machines or a plurality of machines, where theworking operations have to be started, carried out and stopped in acertain sequence or in certain sequences. Sometimes such operations areindependent and sometimes they are dependent on each other as tostarting and stopping points of time, and sometimes series of operationsmust go on simultaneously. In this latter case it can be an advantage,both for technical reasons and for simplicity of description to divide asequence into subsequences.

Control of large production plants with very many operations can be doneby computers, which method is preferable if flexibility is desired.Often there is also the possibility to use specialized or tailor made"control systems, but these systems do not give any flexibility forvariations in the production, and such systems are expensive becausethey must be specially constructed or tailored" for various plants.

Control of small production plants or parts of a production plant, forexample a single multioperation machine or a few machines at aproduction line, often is carried out by specialized control systems,which give very little flexibility for changes in production. Computingor data machines for control are out of the question in such cases, ascomputing machines then are too expensive.

There exist programmable control devices which can be used forsequential control and which give some flexibility. But with theexisting programmable control devices all composite working operationsmust be decomposed in their components, which operation components mustbe ordered specifically one by one from the control device. A result ofthis is that very many signal connections are needed between the controldevice and the working devices of the controlled process and that eachsuch operation must be carried out in many steps. And in general theseprogrammable control devices cannot control simultaneous sequences whichare independent of each other. Besides, sophisticated devices are oftenneeded for signalling from the sensors of conditions, for examplepositions, in the process to the inputs of the control device, forexample when a final position coincides with a starting position.Accordingly, no programmable sequential control system has been hithertoavailable, which is simple in construction and sufficiently flexible inuse, for control of a moderate number of operations.

SUMMARY OF THE INVENTION The present invention relates to a means orsystem for step by step control of a sequence of events or workingoperations and in particular to programmed control of specializedautomates, i.e., special machines which are constructed to carry outseveral working operations on each workpiece automatically.

Sequential control is previously known per se, and sequential controldevices are commercially available in a plurality of different shapes.

Automatic control of for example machining processes is achieved bymeans of either specially made, tailor made," or programmable controldevices. By a specially made" or tailor made" control device is heremeant a control system which is constructed for a particular machine ora particular kind of job. Specially made control systems are usuallyconstructed of details with simple functions, and by use of speciallymade control systems each application calls for individual constructionof the control system. Construction and installation of such controlsystems requires qualified and specially educated and trained personel,and because such control systems very often are very complicated andlaborous to construct, even if the controlled sequence contains a smallnumber of steps, ap plication of such control systems often requires atime consuming and expensive construction and installation work.

The working means and devices and their activating means of the machinesand apparatuses which are to be controlled in many cases occupy the sameposition or condition previous to and after a working operation, e.g.,in controlling a drilling machine. Simple position sensing meanstherefore cannot in such a case recognize the situation previous to andthe situation after a working operation. In known systems for sequentialcontrol it is therefore required to either decompose the workingoperations into simple activities or events, each of which requires anorder signal from the control system, or to include additionalcomponents into and- /or in connection with the control system. Anexample of such decomposing into simple activities is the following:Drilling of a hole by means of a drilling machine can be done by theactivities: fast feeding of the drilling machine to its workingposition, start of the drilling machine, feeding the drilling machineforward at a working rate and finally returning the drilling machine toits original position. So, the number of control steps and stages inknown control systems has to be high, or extra components are required,or both.

Known programmable control systems are in general not capable ofcontrolling sequences which are going on simultaneously and areindependent of each other, and signals of continuous type, so calledD.C.- or resting signals, often cause problems in such systems andrequire special solutions, which make programming more difficult.

Programmable control systems must be reprogrammed, when changes are tobe done in the controlled process. By known programmable controlsysterns which can be compared to the control system according to thepresent invention, the programming requires a relatively great effort byqualified and skilled personel. Known programmable control systems aretherefore expensive in use, as relatively many hours of skilled work arerequired for programming and coupling and testing of programs.

One object of the present invention is to achieve a programmable controlsystem which eliminates the deficiencies mentioned above.

Another object of the invention is to achieve a programmable controlsystem which is specially suitable for replacing specially made controlsystems.

Still another object of the invention is to achieve a programmablecontrol system which is reliable, comparably simple to install and sosimple to program that relatively unskilled personel easily can doprogramming and coupling of programs.

These and other objects are obtained by means of a programmable controlmeans, which comprises at least one program device, at least one controlcircuit, signal connections or communication paths and peripheralequipment, e.g., sensors, detectors, valves, etc., whereby the controlcircuit or the control circuits and the program device preferably arearranged in close contact with each other in such a manner that theytogether form a control unit.

As to the parts of and handling and generating signals said controlcircuit can be divided into an input or logic part, a memory part, whichis controlled by said logic part, and an output part, which iscontrolled by said memory part. Said control circuit has at least threedifferent inputs. One of these inputs will be called the "set input, theother signal input and the third reset input." Said control circuitfurther preferably has two outputs. One of these outputs will be calledorder output" and the other step output."

Said set input and signal input are connected with and control the logicpart, and said reset input is connected to the memory part for zerosetting or resetting the memory part by means of a step signal relatedto that order signal which belongs to the next step in the sequence.

The main characterizing feature of the control means according to thisinvention is that the logic part of said control circuit is soconstructed that input signals applied concurrently to both said setinput and said signal input cause generation of a signal from said logicpart to said memory part only if the input signal of said set inputoccurs previous to the input signal of said signal input. A preferredembodiment of the invention comprises a plurality of control circuits,which preferably are similar to each other with regard to their logicand memory parts. Said control circuits preferably are identical to eachother as to outer dimensions and shape and arranged together in acontrol box," so that they form a modular control unit, in which eachcontrol circuit is a module. Such a module will be called a step module,because each such module is connected with one step of the controlledsequence or sequences.

A particularly preferred embodiment of the invention comprises a controlunit containing a plurality of control circuits and a program devicewhich comprises three program means. One of said program means is thecarrier or the support of an input program which can be changed, thesecond program means carries a fixed or changeable step program, and thethird program means carries a changeable output program. It is expedientto mount this program device on said control box.

Said input program comprises signal paths between the sensing anddetecting means of the working process and said signal inputs as well asprogram components which are needed for achieving the desired inputconditions for each control circuit. Said step program comprises signalpaths which pass directly between the various control circuits from thestep output of a control circuit to the set input of the next circuitand to the reset input of the nearest previous control circuit in thestep sequence of the control circuits, which step sequence thereby isdetermined by the step program. Said output program comprises signalpaths between the order output of the various control circuits andactivating means of the various working means and devices in the workingprocess and program components for achieving the desired outputconditions.

When using any of the embodiments which are mentioned above each controlcircuit or step module is related to one step in the sequence which isto be controlled or one step in some or more of the sequences which areto be controlled by control of simultaneous sequences. Each step of thecontrolled sequence or sequences can consist of a subsequence, that isto say a series of activities, events or working operations. The speciallogic conditions which are formed in each control circuit make itpossible that only one single order is required from a control circuitand that only one signal is required from the sensor for sensing thestate of a working device to a control circuit for each subsequence,even if the subsequence is comprised of a subcycle, that is to say asubsequence with the same starting and final position for the activatingmeans and the sensors which correspond to such a step of the se quence.

By use of said specially preferred embodiment the succession of thesteps can be chosen by programming, that is to say that the successionaccording to which the various control circuits are to be activated canbe chosen at will. Thus it is possible to have jumps over steps, returnsto steps, repeats and alternatives.

In cases when only so called straight forward step succession is inquestion, that is to say that the succession of working condition forthe control circuits coincides with the order of the control circuits inthe control unit, it is expedient to use a step program means with fixedsignal paths corresponding to a straight forward step program.

A control means according to the invention gives a plurality ofadvantages. The number of signal leads to and from the control unit isdecreased in comparison to the number which is required when usingconventional control means, because the control unit according to theinvention does not have to receive a signal from a condition or positionsensing means for every single activity or partial movement within astep in the sequence. Naturally any single activity or partial movementhas to be ordered and then sensed or detected somehow while using thecontrol means according to the invention as well as when usingconventional control means. But, when using a control means according tothe invention it is possible to allow successive activities within aworking operation to control each other directly without any otherinfluence from the control unit than that the control unit starts thefirst of these activities and receives a signal from a sensor after thelast activity within the operation. These activities then together forma step of the sequence. So, one realizes that also the number of stepsin the sequence and the number of orders from the control unit are lowerby control of a number of working operations by means of a control meansaccording to the invention than said numbers are when conventional meansare used. This in its turn contributes to that the logic informationhandling is simplified.

The invention can be used universally for control of sequences ofoperations, and, above all, the process of problem solving, which anycontrol system requires, is simplified.

The sequential control means according to the present invention thus isa much more simple control means for the user than previously knownsequential control means both with regard to installation and use andespecially with regard to the programming.

Other objects and advantages of this invention will become apparent fromthe following detailed description taken in conjunction with theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a block diagram of a controlcircuit or a step module according to the invention;

FIGS. 2a 2e show circuits of principle for different embodiments of theinput part I according to FIG. 1;

FIG. 3a and 3b are logic circuits of two preferred embodiments of acontrol circuit or step module;

FIG. 4a is the circuit of a control circuit comprising fluidistors andother pneumatic components;

FIG. 4b is a control circuit, where the input or logic part is comprisedof a single fluidistor;

FIG. 5 is a block diagram of a modular control means, and FIG. 5 alsoshows an example of control of a working process or sequence containinga certain number of steps;

FIG. 6 is a simplified block diagram of another modular control meansaccording to this invention for control of a working process;

FIG. 7a shows a preferred embodiment of a step module containing acontrol circuit according to FIG. 40;

FIG. 7b shows a modular control unit in section, which control unitcontains step modules according to FIG. 7a in an inner box, which servesas a support for the program device;

FIG. 70 shows a circuit diagram of the air supply to the control meansaccording to FIG. 7b;

FIG. 8a and 8!; show a program device of a similar type as is used inthe control means according to FIG. 7b, the program device of FIG. 8aand 8b having a dif ferent construction than the program device whichcan be seen on FIG. 7b;

FIG. 9a and 9b show symbols for and schematic examples of use of twotypes of pneumatic program components, which can be used in forminginput and output programs;

FIG. 10 shows a part of a filled in program form;

FIG. Ila shows a program in the form of a timedistance-diagram;

FIG. 11b shows the working order or succession of the step modulesaccording to the program of FIG. Ila; and

FIG. He shows a filled in program form which concerns the program ofFIG. lla.

DETAILED DESCRIPTION As can be seen from FIG. I of the drawings thelogic or input part of the control circuit has the reference characterI, the memory part has the reference character II and the output partthe reference character III. Said logic part besides having a set inputi, and at least one signal input 1', preferably also has a start input1', for manual control of the control circuit and start of the controlmeans. The output of the logic part is connected to the l-input of thememory part II. The memory part controls the output part III either viaits 1- output or its O-output depending on the number of inversions inthe control circuit. The output part is preferably also provided with aninput i, for manual control of the output part. Said output partpreferably also has two outputs. One of these outputs, which is calledthe order output" and has the reference it, on the drawing, is arrangedto deliver order signals either directly or indirectly via activatingmeans to working means in the working process.

The other output, which is called step output and has the reference u,on the drawing, is used for achieving the step function of a controlmeans according to the invention, as will be described more in detail inconnection with FIG. 5.

FIG. 2a and 2b are logic circuit diagrams which explain the principle ofthe logic or input part I. Both circuits comprise two inverters l and 2and a bistable circuit 3. The logic part of FIG. 20 also comprises anAND-gate 13 with two inputs, while the logic part of FIG. 21) has aNOR-gate 4 with two inputs. One of said inverters is connected to theset input 1', with its input and to the O-input of the bistable circuit3 with its output. The second inverter 2 is connected with its input tothe signal input 1, and to the l-input of the bistable circuit 3 withits output. In FIG. 2a the I-output of the bistable circuit 3 isconnected to the second input of the AND-gate l3, and in FIG. 2b theO-output of the bistable circuit 3 is connected to one of the inputs ofthe NOR-gate 4. The second input of the gate 13 of FIG. 2a is connecteddirectly to the signal input i, and the second input of the gate 4 ofFIG. 2b is connected to input 1', via NOR-gate 2. From FIG. 20 it can beseen that the logic part sets two conditions for an output signal to bedelivered from the logic part to the memory part. One of theseconditions, which one for simplicity may be called the primarycondition," implies that input signals must be present simultaneously onboth the set input i AND the signal input The second condition, whichfor simplicity may be called the secondary condition," implies that theinput signal of the set input must be present previous to the inputsignal at the signal input. One then has presumed that the bistablecircuit 3 is of such a type that it is held by the signal which arrivesfirst in a state which is determined by this signal. The input signalscan be of either the level type or the pulsed type.

In FIG. 2b the function of the AND-gate I3 is replaced by two inversionsand a NOR'function. One of the inversions is obtained in that thell-output of the bistable circuit is used instead of the l-output, andthe other inversion is carried out by the inverter 2.

FIG. 20 shows a simpler input part, which comprises a trigged pulsegenerator I4 and an AND-gate 13. In this circuit the secondary conditionis achieved in that the pulse generator I4 is responsive only to or isfed with either negative or positive signal jumps depending on whetherthe sensor which is connected to the signal input i, delivers a negativeor positive going signal when the corresponding working device occupiesits final position after a working operation. The AND-condition of thiscircuit is achieved in the same way as in the circuit of FIG. 2adirectly by means of an AND-gate 13.

FIG. 2d shows a simple way of achieving the logic conditions, i.e., theAND-condition plus the secondary condition, by means of a pneumatic,four-way valve having two control inputs and return by means of aspring. From FIG. 2:! one also can see that an output signal is obtainedif the signal of the set input i, arrives previous to the signal of thesignal input i and if both signals thereafter are simultaneously (orconcurrently) present.

FIG. 2e shows a circuit having a relay with two windings for achievingthe logic conditions. The set signal is fed to one of the windings andthe sensor signal to the other winding in such a way that said twosignals oppose each other in the relay. With substantially the samemagnitude of both signals the relay will not be activated, if the sensorsignal arrives before the set signal. So, also this circuit delivers anoutput signal only if the set signal arrives first and if both the setsignal and the sensor signal thereafter exist simultaneously.

In the logic circuit diagram of FIG. 3a the input part I is essentiallythe same as in FIG. 2b. An OR-gate 5 has been inserted between theNOR-gate 4 and the memory part II to make it possible to arrange aninput i for manual control of the memory part II of the control circuitand to start the control means. The control circuit has two inputs forsensor signals, one of which is an active input i and the other is apassive input i,,, which inputs will be described in more detail inconnection with FIG. 4a. The memory part II consists of a bistablecircuit or a memory 6 and an OR-gate 7 with two inputs i and i, forzeroor resetting of said memory 6. The extra reset input i is used in amodular control unit for centrally fed zeroor resetting. That is, resetinput i provides a resetting signal which is fed from a central locationwhich is common to all modules, when starting the control means, to makesure that all the control circuits of the control means are reset at thestart of the control means. The memory 6 is connected with its 1- outputto the output part III, whereby the l-output is connected directly tothe step output u as well as either directly by means of a signal lead 8or indirectly via a pulse generator 9 to an amplifying device 10, whichcomprises an OR-gate 11 with two inputs followed by an amplifier 12. Theoutput of said OR-gate 11 is connected to the input of the amplifier 12,the output ofwhich is the order output u, of the control circuit.

The second input of the OR-gate 11 serves as said input i. for manualcontrol of the output part [II of the control circuit. By manual controlvia said input 1', an output signal is obtained only on the order outputu and not on the step output 14,. The timing device 9 can be used forpulsing the output signal, this being symbolized by a pulse generator 9'in the drawing, or to delay the output signal, this being symbolized bya delay means 9" on the drawing. Said timing device can be replaced witha device which gives a direct connection between the memory part II andsaid amplifying device 10, this being indicated on the drawing by abypass connection 8.

The logic circuit diagram of FIG. 3a is very well fit for realization bymeans of fluidistors and other pneumatic components.

FIG. 3b shows a circuit diagram of a control circuit which is suitablefor realization by electric or electronic, preferably integrated,circuits, for example monolithic circuits. The logic part of thiscontrol circuit comprises two inverters l6 and 18 and a monostablccircuit 19, for which the stable condition is denominated itsfl-condition. The input of the inverter 16 forms the set input i, of thecontrol circuit, and the trigger input of the monostable circuit 19forms the signal input i, of the control circuit. The output of theinverter 16 and the l-output of the monostable circuit 19 areinterconnected in a point 17. This interconnection point 17 is connectedto the input of the inverter 18. By means of the interconnection 17 anAND-condition is achieved without the use of extra gates for this. Saidset input 1', is arranged to respond to a negative signal jump, and saidsignal input i, is arranged to respond to a positive signal jump. Thememory part II of said control circuit consists of a bistable circuithaving two NAND-gates 20 and 21 in a well known connection. The bistablecircuit II has two trigger inputs and two outputs. One of the triggerinputs is connected to the output of the inverter 18, and the othertrigger input is the reset input i, of the control circuit. One of theoutputs of the memory part is connected to the trigger input of amonostable circuit 22 of the output part III for causing a pulsed outputsignal. The stable state of said monostable circuit may be called its0-state. The corresponding 0-output serves as an extra order signaloutput u,'. The second output of the memory part II serves as the stepoutput it, of the control circuit. For amplifying the order signal theoutput part also is provided with an amplifying device, which comprisesan inverting buffer stage 23 and an inverting amplifier 24 in cascade,whereby the output program is inserted between the output 26 of saidinverter 23 and the input 27 of said amplifier 24. The input 25 of saidinverter 23 is connected via an outer coupling either to the extra ordersignal output u,, if a pulsed output signal is de sired, or to the stepoutput 14,, if a continuous output signal is desired.

The control circuit S which is shown in FIG. 4a, corresponds to thelogic circuit diagram of FIG. 3a. The logic and memory parts I and II ofthis control circuit together consist of an integrated circuit havingsix fluidistors F, F and the output part III consists of other types ofpneumatic components. Said fluidistor F corresponds to the inverter 1,the fluidistor F corresponds to the inverter 2, the fluidistors F and Ftogether form a bistable circuit, which corresponds to the bistablecircuit 3, and the fluidistor F corresponds to the NOR-gate 4 accordingto FIG. 3a and FIG. 2b. Said fluidistor F, corresponds partly to thebistable circuit 6 of said memory part and partly to the OR-gates 5 and7 according to FIG. 3a. The step output :4, of the control circuit canbe connected either directly to the output d, of the fluidistor F as isshown in FIG. 4a, or to an amplifier, e.g., a fluidistor F, (not shownin the drawing), which receives its input signal from the fluidistor FFrom FIG. 40 it can be seen that the fluidistor F: has two inputs a andb, Input a is connected to the passive input 1' of the control circuit.An input signal to this input i is achieved by means of appropriatesensors which indicate that the air has a predetermined control pressureor so called low pressure." The other input b, of the fluidistor F, isconnected to a venturi or ejector element 28, which, on the one hand isfed with pressurized air and on the other hand is connected to the inputi, of the control circuit, input i in this manner being an active input,which implies that an input signal occurs at this input by breaking theair flow which flows out of the input i when no input signal is present.Said air flow can be broken for example by a sensor valve which tightensa signal lead which is connected to the input 1' whereby a pressure riseoccurs at the input 1' without supplying air via said sensor valve. Suchan active input gives the possibility of using simpler sensors, gives amore reliable function and is far better from a safety point of viewthan a passive input. In one embodiment of the invention the passiveinput has been removed completely. This embodiment is not shown in thedrawings.

The advantage of using a venturi or ejector element 28 for achieving anactive input is that longer signal leads can be allowed than if abranching is used to this end.

The logic and memory part according to FIG. 4a is best described throughthe following signal or truth table (page l9a), where each fluidistorhas two to four columns for input and output signals. The inputs of thefluidistors are designated with a, b, a and b, the outputs of thefluidistors are designated with c and d, and these designations alsohave got an index which corresponds to the index of the designations ofthe fluidistors. Even the fluidistor F which is mentioned above isincluded in the table.

The output d of the fluidistor F is connected to the step output it, aswell as either directly to an amplifying device 10 or to a timing device9, which is arranged to control the amplifying device 10, the output ofwhich is the order output u of the control circuit. The timing device 9comprises a controllable exhaust valve 29 having a return spring, a timecircuit comprising a choke device 30 in series connection with a volume31, a controllable valve 32 for pulsing the output signal and a chokedevice 34. In practice the timing device is constructed tion between thefluidistor F and the order output u,. To change the timing device from apulse device into a delay device is done by changing the timing deviceitself.

The amplifying device 10 in FIG. 4a consists of a pilot valve 35, whichis fed with pressurized air via a choking device 36, and a controllablevalve 37, which has two positions and which is arranged to be controlledby the pilot valve 35 in such a manner that the valve 37 causes a signalon the order output a, in response to the output signal of thefluidistor F Said pilot valve has an input, which is connected to thetim ing device 9 and an output, which is connected to the valve 37, aswell as an active input, which constitutes said input 1', for manualcontrol of the amplifying device It) by means of an operating means, bymeans of which the air flow from said input i can be stopped.

In the control circuit which is shown in FIG. 4b, the fluidistors F, Fof FIG. 4a are replaced by a single fluidistor F. Said fluidistor F canbe of a proportional or analogue type in contrast to the fluidistors F,F which should be of the switch type. A feed-back from one of the twooutputs-of said fluidistor to one of its three inputs causes blockingholding and no other response to other signal conditions than the signalcondition which is stated above, so that the fluidistor delivers asignal via its second output to the memory part [I only if the setsignal occurs previous to the sensor signal and both signals thereafterare present simultaneously. The control circuit has an active sensorsignal input i and no passive sensor signal input. In this embodiment,as in the embodiment of FIG. 4a, the input i is an active TABL E Modulsignals iz ii is 112 Fluidistor F: F: Fl F4 F5 Ft Fr In and outputs Ine: an b; (a hi or a; In at d. at b5 ('5 an bs de in Remarks The table isvalid in the direction of the arrow only. 0 1 1 t] 0 I) 1 I 0 0 I I 1 (I0 I 0 (l 0 l1 =lz=l), i3=1(start).

. I) I I 0 fl 0 I 1 l) (I I I 1 I) I] 0 I) ll 0 ll =l2=i:=(]. I) I 1 I 0I I) (l (J I I) O l 0 D I) (l (I 0 l =1 firstly. 1 0 I) I I] I I) fl 0 I0 I) O l l II 1 I I Iz=l secondly. I) I I I) (l I] I I II (I I I 1 I) Ul') 1 1 I I) I l I) I) (I I I I) II I l I O 0 I t) l) I) I) 1 I I] I) I)l l I) ll I I I l) I) (l (I U 0 (l 1 1 I I ll 1 (I I) 1 ll I] I 0 L) I)(l I] O I 0 (l l (J I I) I) (J l I) (l t] I 1 I) I I 1 (l l) l (l l I)I) (I l U I) I) l l I I) O (l (l I l (I (I (l I 1 ll (1 I 1 1 (I l) I) 0fl 0 =0. 1 0 I) ll 1 (l I l 1 U I I I) (l U I) I) ll l) lz=l IIIS ly. 1O U U 1 i (l (J I I) I l I) l) I) U (l l) I) i1 1 secondly.

as a single component or unit. The timing device 9 can be used eitherfor delaying or pulsing the output signal. These two possibilitiestogether with the possibility of direct connection between thefluidistor F, and the amplifier I0 is indicated by the symbol of a valve33 having three positions. In the indicated position the valve 33 isconnected to give a pulsed output signal. If the valve symbol is movedupward, so that the lower square of the valve symbol replaces the centersquare, the valve is connected to delay the output signal, and if thevalve symbol is moved downward, so that the upper square replaces thecenter square, the valve gives a direct connection between thefluidistor F, and the amplifier 10. In practice the latter situation isobtained by taking the timing device away from the step module andreplacing it with another unit having substantially the same outer shapeand dimensions as the timing device and having a channel which gives adirect connecinput, while the other inputs r',, i i and i can be passiveinputs. The output part III of the control circuit according to FIG. 4bsuitably is similar to the output part according to FIG. 4a.

The control means of FIG. 5 comprises a number n of control circuits orstep modules 5,, S S... The program of said control means is divided inthree parts, namely an input program, a step succession program and anoutput program, which programs are arranged separately on correspondingprogram means or program carriers 9,, P,, P;,, respectively, by means ofsignal leads and program components. A hand valve 38 is arranged forstart of the control means, and a hand valve 39 having two stable statesmakes it possible to choose between automatic repetition of thecontrolled sequence and automatic stop of the control means after havingpassed through the sequence once. The sequence or working process 40,which has been chosen as an example, does not require any jumps, repeatsor alternatives as to selection of control circuits. Said control meanstherefore operates according to a straight forward step succession. So,the step program is connected as a straight forward program, and each ofthe control circuits is associated with a corresponding step in thesequence. The working device of each step of the sequence is a motor,which on the drawing has been indicated as a linear motor or a pneumaticcylinder. Each motor has the reference character M and an index whichindicates the number of the step in the sequence. The activating meansfor each motor consists of a directional valve, which has the referencecharacter V and an index corresponding to the number of thecorresponding step. Each step or stage comprises a limit sensor forsensing the starting position and a limit sensor for sensing theforemost position of the motor, which sensors are designated with G, and0,, respectively, and a second index corresponding to the number of thestep. The terminals of the control circuits have the same referencecharacters as in FIG. 4a and furthermore a second index corresponding tothe number of the control circuit, which in the selected example isequal to the number of the corresponding step in the sequence.

The dividing into three parts of the total program and the special logicof the control circuits result in very uncomplicated program componentsand a very simple programming.

The control means in FIG. 5 operates as follows. Suppose that thecontrol means has been connected to its air supply. Then each controlcircuit occupies its zero or starting position, which implies that noneof the control circuits delivers an output signal, that is u, u, if thesignals are given the same denominations as their correspondingterminals. To start the control means a signal is given by means of thevalve 38 to the start input 4' (corresponding to i, in FIGS. 3a and 4a)of the first control circuit 8,. The start inputs of the rest of thecontrol circuits are not used in this example. Said first controlcircuit S, then delivers an output signal or order u,, via the outputprogram to the directional valve V,, which activates the motor M,. Atthe same time, the control circuit delivers a step signal u,,, whichgoes via the step program to the set inputi of the next control circuitS, in the sequence, for which said step signal is the set signal. Thestep signal u,, is also fed and to the reset input i of the "preceding"control circuit S,,, for which said step signal is the reset signal. Asthe working device M, of the first step has a starting position which isequal to the final position when the order arrives, there is a signal onthe input i of the control circuit 8, when the set signal arrives to theinput i,,. This does not satisfy said secondary condition, and thereforethe control circuit S, remains in its starting or resting position. Whenthe motor M, gets into its foremost position, the limit sensor 6,,delivers a reset signal to the directional valve V,, which results inthat M, returns to its starting position. And that completes the firststep of the sequence. This step also may serve as an example of asubsequence, which in this case consists of a subcycle as the finalposition coincides with the starting position, and which contains thetwo activities: forward movement and return of the motor M,. Thanks tothe secondary condition the next control circuit S, is able todiscriminate between the beginning and the end of the subsequence. So,the control circuit S, does not start until the position sensor 0,,again dctivers a signal to the signal input i,,, whereby this controlcircuit delivers an order signal u,, and a step signal u,,. The ordersignal 14,, goes to the directional valve V,, which activates the motoror cylinder M,. The step signal is passed to the input i,, of thecontrol circuit S, and resets this circuit, i.e., resets its memorypart, as well as to the input i,, to prepare the third control circuitS, in such a manner that this circuit will respond to a sensor signal.When the motor M, operates the position sensor G,,, the control circuitS, receives input signals which satisfy the secondary condition, wherebyS, is activated. Then the preceding control circuit S, is reset and thenext control circuit S, (not shown) receives a set signal from theoutput u,,. From the output u,, a signal or order is delivered to thedirectional valve V, with the result that the motor M, starts. Thissignal is also passed to the directional valve V, of the preceding step,where it serves as a reset signal for V, with the result that the motorM, returns. The valve V, is reset by means of a return spring when thesignal 14,, disappears.

This example thus also demonstrates three different ways for resettingthe directional valves. V, is reset by means of a signal from the limitsensor 6,, belonging to the same step as the directional valve V Thesecond directional valve V, is reset by means of an order from thecontrol circuit 8, belonging to the next step of the sequence. And thethird directional valve V, is reset, as has already been mentioned, bymeans of the return spring of this valve. Of course other combinationsare possible, especially by irregular step succession.

For example the directional valves or activating means V, and V, shouldbe of a bistable type. To use bistable activating means gives theadvantage that pulsed order signals can be used and the advantage that amemory function is obtained. Besides, if pulsed order signals are used,a bistable activating means can be operated back to its startingposition at any moment, except during the order pulse time, withoutregard to the condition of that control circuit which is arranged togive the working order to said activating means.

It is possible to use bistable activating means and pulsed order signalsin the majority of control problems. The output program becomes simpler,if bistable activating means and pulsed order signals are used, and thisis of special advantage by simultaneous sequences and also by othertypes of irregular step succession.

Only the active signal input of the control circuits is used in theexample which has been described above.

FIG. 5 also shows an example of forming an AND- condition in the inputprogram. The fourth control circuit S, shall not start until the sensor0,, indicates that the motor M,, which belongs to the second step, againhas taken its starting position AND the sensor 6,, indicates that M,,which belongs to the third step, has taken its foremost position.Through this measure it is checked that the order which is given by thethird control circuit S, is carried out.

The. branching of the signal from the output 14,, is an example ofoutput programming.

The active condition of the control circuits is moved step by step fromone control circuit to the next one until the active condition reachesthe last control circuit S,,. If the hand valve 39 occupies the positionwhich is indicated on the drawing, the sequence will be repeated. If thevalve 39 is thrown into its other posi-

1. A sequential operation control means having a plurality of controlcircuits of which each control circuit controls only a single discretesuboperation and said control circuits are activated successively andsingly in a step-wise manner to deliver an order signal corresponding tothe suboperation assigned thereto in response to receiving a sensorsignal indicating a predetermined state of the subopeRation assigned toa preceding control circuit in the succession, further comprising: meansfor delivering concurrently with said order signal a set signal to thenext control circuit in the succession; and a signal orderdiscriminating subcircuit in each said control circuit responsive to thearrival of said set signal from a preceding control circuit and of saidsensor signal from the suboperation being controlled by the saidpreceding control circuit, the latter control circuit being activatedif, and only if, said set signal from said preceding control circuit ison before said sensor signal becomes concurrent therewith.
 2. Asequential operation control means comprising: a plurality of controlcircuits, each of which controls only a single discrete suboperation andsaid control circuits are activated successively and singly in astep-wise manner to deliver an order signal corresponding to thesuboperation assigned thereto, each control circuit including a logicsection, a bistable memory section coupled to said logic section, anoutput section coupled to said memory section, said output sectionproviding an order output signal and a step output signal in response tosetting of said memory section, a first input and a second inputconnected to said logic section, a signal order discriminating circuitin said logic section responsive to the arrival of signals at both saidfirst and said second logic circuit inputs for causing a set signal tobe delivered from said logic section to said memory section if, and onlyif, the signal at said first logic circuit input is on before the signalat said second logic circuit input becomes concurrent therewith, and athird input coupled to said memory section for resetting said memorysection; means for supplying an operation sensor signal; sensor signalprogram means coupled to said second input of said logic circuits and tosaid means for supplying said operation sensor signal, and includingfirst means for selective interconnection thereof; step signal programmeans coupled to said first input of said logic circuits, to said thirdinput and to said step signal outputs of said control circuits, andincluding second means for selective interconnection thereof; means forsupplying an operation order signal; and output signal program meanscoupled to said order signal outputs of said control circuits, to saidmeans for supplying said operation order signal, and including thirdmeans for selective interconnection thereof, to thereby control saidsuboperations.
 3. Control means according to claim 2, wherein each ofsaid control circuits have similar logic and memory sections and areconstructed as control unit modules (St; St1, St2, . . . ).
 4. Controlmeans according to claim 2, wherein said logic section and said memorysection of a control circuit are comprised of fluidistor means, andwherein said logic section includes at least one active input which isactivated by signals from said sensing means, and including means forselectively blocking air flow from said active input.
 5. Control meansaccording to claim 4, wherein said logic section contains first throughfifth fluidistor means of the OR/NOR-type, at least the third throughfifth fluidistor means having a first (a) and a second (b) input and allfluidistor means having a first (c) and a second (d) output, and whereinsaid memory section includes a sixth fluidistor means of a bistabletype, the first fluidistor means of said logic section being arranged toinvert input signals fed to the first input of the control circuit andarranged to control the first input of the fourth fluidistor means ofsaid logic section by its first output (c1), which fourth fluidistormeans via its second input (b4) is controlled by the first output (c3)of the third fluidistor means and which fourth fluidistor means via itsfirst output (c4) is connected to the second input (b3) of the thirdfluidiStor means and via its second output (d4) to the first input (a5)of the fifth fluidistor means, a second fluidistor means being arrangedto invert input signals fed to either an active or a passive secondinput of the control circuit and arranged to control by its first output(c2) the first input (a3) of the third fluidistor means and the secondinput (b5) of the fifth fluidistor means, whereby the third, fourth andfifth fluidistor means form said discriminating circuit for controllingthe second input (b6) of the sixth fluidistor means of said memorysection.
 6. Control means according to claim 4, wherein saiddiscriminating circuit in the logic section of said control circuit iscomprised of a single fluidistor means, and including a positivefeedback means for blocking holding except when the signal fed to saidfirst logic circuit input occurs earlier than the input signal fed tosaid second logic circuit input.
 7. Control means according to claim 2,wherein said control circuit is comprised of electrical elements. 8.Control means according to claim 7 wherein: said logic section of saidcontrol circuit comprises a first (16) and a second inverter (18) and amonostable multivibrator (19); said first inverter being arranged to beactivated via the first input (i1) of the control circuit by means of anegative going signal or lack of signal and said monostablemultivibrator (19) being arranged to be triggered via the second input(i2) of the control circuit by means of a positive going signal or bythe presence of a signal from its stable state, which is the 0-state,into its 1-state; the output of the first inverter (16) being connectedwith the 1-output of the monostable multivibrator by means of which alogical AND-condition is achieved; and the second inverter (18) havingits input connected to the interconnection point (17) between saidmultivibrator and said first inverter (16) and being arranged to controlthe memory section of said control circuit; said memory sectioncomprises a bistable circuit having two NAND-gates (20, 21); and saidoutput section comprises a monostable circuit (22) having a triggerinput; one of the outputs of said memory section being connected to thetrigger input of said monostable circuit (22) belonging to the outputsection for generating a pulsed output signal (u1''), and the secondoutput of said memory section being connected directly to the stepoutput (u2) of said output section, whereby pulsed or DC order signalsmy be selected by connecting either the pulsed output (u1'') or the stepoutput (u2) to one or more activating means of the controlled processvia said output signal program means.
 9. Control means according toclaim 8 wherein said output section includes an inverting buffer stage(23) and an inverting amplifier (24) coupled to at least one of thepulsed or step signal outputs.
 10. Control means according to claim 7wherein said logic section comprises a relay connected such thatblocking against activation or blocking holding is obtained except whenthe signal fed to said first input occurs before the input signal fed tosaid second input.
 11. Control means according to claim 10 wherein saidthree program means are combined to form a connecting terminal devicefor coupling the three programs, which terminal device is common to saidprograms and further serves as a support for program components and as aconnecting device for connecting said program means with said controlcircuits.
 12. Control means according to claim 2 wherein said logicsection comprises a controllable, double throw, four-way valve havingpositive feedback such that it will be blocked against setting or willbe held in its set condition for all conditions except when the inputsignal of said first input occurs earlier than the input signal of saidsecond input.
 13. Control means according to claim 2 wherein saidprogRam means comprise connecting terminal devices for coupling ofprograms, direct or indirect coupling of program signals to said controlcircuits, said control circuits and said program means forming a controlunit.
 14. Control means according to claim 2 comprising non-returnvalves connecting said step signal program means to respective stepoutputs.
 15. Control means according to claim 2 comprising non-returnvalves connecting said step signal program means with respective firstand third inputs of said control circuits.
 16. Control means accordingto claim 2 wherein said step signal program means is provided with fixedsignal connections according to a desired step sequence program. 17.Control means according to claim 2 comprising a bistable activatingmeans coupling said control circuits to the suboperation means.
 18. Asequential operation control means having a plurality of controlcircuits of which each circuit controls only a single discretesuboperation and said circuits are activated successively and singly ina step-wise manner to deliver an order signal to the suboperationassigned thereto in response to receiving a sensor signal indicating apredetermined state of the suboperation assigned to a preceding controlcircuit in the succession, further comprising: means for supplyingoperation sensor signals; means for supplying operation order signals;means in said control circuits for delivering concurrently with saidorder signal a set signal for the next control circuit in thesuccession; means in said control circuits for delivering concurrentlywith said order signal a reset signal for a preceding control circuit inthe succession; a sensor signal program switchboard means connected tosaid control circuits and to said means for supplying operation sensorsignals; means connectable to said sensor program switchboard means forpermutating said sensor signals; an output signal program switchboardmeans connected to said order signal delivering means of said controlcircuit and to said means for supplying operation order signals; meansconnectable to said output signal program switchboard means forpermutating said order signals; a set and reset signal programswitchboard means connected to said control circuits; and meansconnectable to said set and reset signal switchboard means forpermutating said set and reset signals.
 19. A sequential operationcontrol means according to claim 18 wherein said control circuits eachinclude a logic section, a memory section coupled to said logic section,an output section coupled to said memory section, said output sectionproviding respectively an order output signal, a set output signal, anda reset output signal, first and second inputs connected to said logicsection for receiving respectively a set and a sensor signal, and asignal order discriminating circuit in said logic section responsive tothe arrival of signals at both said first and second logic circuitinputs for causing said order, set, and reset signals to be deliveredif, and only if, the signal at said first logic circuit input arrivesbefore the signal at said second logic circuit input.